HP 3000 Manuals HP 3000 Manuals
CKOPENSHR
A call to CKOPENSHR initiates file processing with dynamic locking and
shared access allowed.
CALL "CKOPENSHR" USING filetable, status
In order to process a KSAM file with shared access and dynamic locking,
the file must be opened with a call to CKOPENSHR. CKOPENSHR is exactly
like CKOPEN in that it initiates processing, specifies the type of
processing, and specifies the access mode. The file must have been
created previously with the BUILD command of program KSAMUTIL (refer to
section II).
To open a file for shared access means to make it available for
processing by more than one user. Shared access allows all users to read
or position the file, but only one user at a time can modify the file by
writing new records, or rewriting or deleting existing records. To
insure that more than one user does not attempt to modify the file at the
same time, you must call CKLOCK to dynamically lock the file before
calling the procedures CKWRITE, CKREWRITE, or CKDELETE. After modifying
the file, you should call CKUNLOCK so that it can be accessed by other
users.
PARAMETERS
filetable an 8-word record containing the name of the file, its
input-output type, and access mode. When the open is
successful, the first word of this table is set to the
file number that identifies the opened file. (Refer to
Filetable Parameter discussion earlier in this section.)
status one word (two 8-bit characters) set to a pair of values
upon completion of the call to CKOPENSHR to indicate
whether or not the file was successfully opened and if
not why not. Left character is set to "0" if open is
successful, to "9" if not. Right character is to"0" if
open is successful, to file system error code if not.
(Refer to Status Parameter discussion earlier in this
section.)
USING CKOPENSHR
Except that CKOPENSHR allows shared access and dynamic locking, and
CKOPEN does not, a call to CKOPENSHR operates exactly like the call to
CKOPEN. Upon successful execution of CKOPENSHR, the file named in
filetable is available for the type of processing specified in file-
table. Before the file is opened successfully, no operation can be
performed that references the file either explicitly or implicitly.
A file may be opened by CKOPENSHR for any of the access modes
(sequential, random, or dynamic) and for any input-output type (input
only, output only, or input-output) allowed with CKOPEN.
Refer to the description of using CKOPEN for the specific affects of
opening a KSAM file with the various input-output types and access modes.